Some counties have bumper crop of 'hoppers

ONIDA - If you have been watching the cars come across the bridges at either Whitlock or in Pierre, chances are that the bumpers and license plates were just plastered with grasshoppers. Extension Educator Mike Huber in Dewey County told me that they have been having quite a problem with grasshoppers eating the crops and rangeland grasses. Even though Lake Oahe is two miles wide or more in places, it doesn't seem to be a problem for the grasshoppers to fly across into Potter and Sully Counties. Many farmers and ranchers have been spraying for them already. Dr. Sue Blodgett, head of the SDSU Plant Science Department, came to Sully County for a visit last week. I suggested we take a tour of the SDSU Sunflower Trials and the SDSU Winter Wheat CPT Trials located here. Being the entomologist that she is, she reminded me to bring my sweep net to check for the different insects. We found adult Dectes longhorn beetles in the sunflower, but what we found in the sweep net at both locations was primarily grasshoppers. The grasshoppers were in all stages of development, from the tiny nymphs to full-grown adults. Many species of grasshoppers are general herbivores and feed on a variety of plants, while some like only grasses. Mike Catangui, SDSU Extension entomologist, was quoted in an article by Jeff Bunn in the Pierre Capital Journal: “The damage due to grasshoppers is analogous to hail. It removes the leaves that manufacture the food for the plant. Right now we're not too worried, because the plants are still young. Within three weeks, that's when the concern starts for soybean and corn.” At present, we are at that most vulnerable stage for corn and soybean (i.e. tasseling for corn and flowering for soybeans.) Sue Blodgett told me that the most vulnerable place on a wheat plant is on the culm right below the spike. If it is green and succulent, the grasshoppers will chew it until the head falls to the ground and is lost. Dr. Dwayne Beck offers the following simple, yet to-the-point advice: “You scout them, count them and spray the edges [of your field] for sure.” For the publication, “Economic Thresholds in Soybeans - Grasshopper and Bean Leaf Beetle,” go to http://agbiopubs.sdstate.edu/articles/FS905.pdf . For insecticides for grasshopper control on soybeans, see Table 1. Another web site is http://www.ag.ndsu.nodak.edu/aginfo/entomolgy/entupdates/ICG_09/24_cropchart09.pdf. Look for insecticide products - quick reference charts for grasshopper. For more information on economic thresholds, contact your local Extension office.